<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>

    <h1>注册页面</h1>

    <script>
        const xhr = new XMLHttpRequest();
        xhr.open('post', '/api/b', true);
        xhr.setRequestHeader('content-type', 'application/x-www-form-urlencoded');
        xhr.send('username=y11y&password=122223');
        xhr.onreadystatechange = function () {
            if (xhr.readyState === 4 && xhr.status === 200) {
                console.log(xhr.responseText);
            }
        }
    </script>

</body>

</html>